1. Field of the Invention
The present invention relates to an image communication apparatus and an image communication program using a communication network, particularly to a technique of optimizing the quality of the image data for communication, using the signal provided by the communication network.
2. Description of the Related Art
In recent years, with the development of the Internet protocol communication network (including the Internet), an apparatus equipped with a facsimile communication function utilizing this communication network has come into commercial use. Further, the VoIP (Voiceover Internet Protocol) communication technique wherein communication of audio data is carried out via the Internet communication network has come into widespread use. Particularly the communication based on this technique is called the IP (Internet Protocol) telephony.
When the Internet is used, a contract agreement is with a carrier (provider) based on a flat rate scheme in many cases. In VoIP communication, an addition charge may be imposed, depending on the destination of communication, even if the contract agreement is made based on a flat rate scheme. For example, if the VoIP carrier at the source of communication is the same as that on the destination, VoIP communication is free of charge (without extra charge). If the destination is a public telephone network or a VoIP carrier different from that on the source side, the VoIP communication is carried out on a paid basis (with extra charge). Further, a lower rate may be determined for the VoIP communication between particular VoIP carriers according to the agreement among such carriers. To meet such a situation, in the VoIP communication, an audio signal or the like is used to notify a user of the charge information, showing if the communication is free or not, or if the communication charge is higher or lower, depending on the destination.
In the meantime, the technique of utilizing charge information in the image data communication is exemplified by the one (e.g. Patent Document 1) wherein, for one and the same destination, the communication charge for sending image data via the public telephone network and that for sending image data via e-mail using the Internet facsimile function by dial-up connection with the IP network are separately calculated. The results of calculation are compared with each other, and are notified to the user so that the user can select the most desirable communication medium.
[Patent Document 1]                Tokkai 2000-3584058 (Japanese Non-Examined Patent Publication)        
However, the technique disclosed in the Patent Document 1 requires the communication charge to be calculated for each communication medium prior to initiation of communication, and requests the user to select a communication medium. This has involved complicated processing and operation.
In the aforementioned technique, communication media are switched according to the communication charge, and communication charge cannot be reduced on condition of using one and the same communication medium. For example, in the image communication such as facsimile communication, the exchange of capabilities such as image quality and encoding method is carried out with the destination of communication after establishment of communication. Based on the result thereof, the image data output attribute (such as image quality and encoding method) is determined. Thus, even when communication is performed on a free basis or on a paid basis, depending on the destination, as in the VoIP communication, there is an increase in the amount of image data to be sent and in the communication charge on a paid basis, if the encoding method of lower compression rate and higher picture quality are determined as a result of exchanging the capabilities. Such problems have been left unsolved in this conventional art. Further, the output attribute can be determined only after exchange of capabilities. This arrangement has failed to convert the image data quality in the earlier phase.